Ray Tune warnings

[iacobo]

Ray Tune produces the following warnings:

INFO registry.py:66 -- Detected unknown callable for trainable. Converting to class.
WARNING experiment.py:295 -- No name detected on trainable. Using DEFAULT.

Non-fatal, but it's annoying to have these messages bloating the console output.

[iacobo]

https://docs.ray.io/en/latest/_modules/ray/tune/registry.html

[krfricke]

I've filed this PR to tackle this issue: ray-project/ray#21518

Note however that we generally recommend using tune.with_parameters instead of functools.partial, as the latter will re-serialize the data for every new trial. tune.with_parameters will store the data in the object store and each trial will access the same object, which should be much more efficient.